Valves are known for controlling a flow of a fluid therethrough. Valves may be operated manually, or actuated by electrical, pneumatic, or hydraulic means, and include at least two ports through which the fluid passes. Fluid enters the valve through a first port, and, when the valve is in the open position, exits the valve through a second port. Fluid does not flow through the valve when the valve is in the closed position. Valves that include more than two ports may redirect the fluid among multiple piping subsystems connected to the ports.
Generally, a valve includes a valve body with at least two ports, a multi-position valve member that controls the flow of fluid through the valve body, and a handle or an actuator that is attached to the valve member via a valve stem. In the open position, the valve member does not prevent fluid flow, while in the closed position, the valve member is received by a valve seat and prevents the fluid from flowing from one port to the other port. Because the valve stem is a moving component, packing material, seals, gaskets, or other similar materials or structures known in the art, typically seal the valve stem to prevent fluid from leaking out of the valve. In some actuated valves, a leak port may be coupled to a chamber that houses the valve actuator to detect when fluid has undesirably migrated from the chamber that houses the valve member, along the valve stem and into the chamber that houses the actuator. The leak port can detect other types of valve failures, and may be coupled to other valve chambers as well.
Helium may be used to detect valve leaks by charging the piping system with helium, actuating the valve and checking the leak port with a helium leak detector. In certain applications, however, helium leak testing may not be practical. For example, a piping system that includes a cryogenic gas as the working fluid, such as CO2, may be located within an isolated and sealed environment that is maintained at a very low dew point. In such a system, the valve leak port may not be accessible, charging the piping system with helium may not be convenient, and even visual inspection of the valve during normal operation may not be possible, since leaking CO2 would not cause frost to form on the valve near the leak port due to the very low dew point of the environment.
An improved mechanism to detect valve leaks and failures in certain applications is desired.